Battery cell of novel embedded type structure

ABSTRACT

Disclosed herein is a battery cell including an electrode assembly of a cathode/separator/anode structure, the electrode assembly being impregnated with an electrolyte, the electrode assembly being chargeable and dischargeable, a battery case in which the electrode assembly is mounted, the battery case being made of aluminum or an aluminum alloy, and an alumina coating layer applied to at least a portion of an outer surface of the battery case by anodizing.

TECHNICAL FIELD

The present invention relates to an embedded type battery cell, and,more particularly, to a battery cell including an electrode assembly ofa cathode/separator/anode structure, the electrode assembly beingimpregnated with an electrolyte, the electrode assembly being chargeableand dischargeable, a battery case in which the electrode assembly ismounted, the battery case being made of aluminum or an aluminum alloy,and an alumina coating layer applied to at least a portion of an outersurface of the battery case by anodizing.

BACKGROUND ART

As mobile devices have been increasingly developed, and the demand forsuch mobile devices has increased, the demand for secondary batteries asan energy source has also sharply increased.

Depending upon kinds of external devices in which secondary batteriesare used, the secondary batteries may he used in the form of a singlebattery or in the form of a battery pack having a plurality of unitcells electrically connected to on another. For example, small-sizeddevices, such as mobile phones, can be operated for a predeterminedperiod of time with the power and the capacity of one battery. On theother hand, a battery pack including a plurality of batteries needs tobe used in middle or large-sized devices, such as laptop computers,portable digital versatile disc (DVD) players, small-sized personalcomputers (PCs), electric vehicles, and hybrid electric vehicles,because high power and large capacity are necessary for the middle orlarge-sized devices.

Among secondary batteries, a lithium secondary battery is widely usedsince the lithium secondary battery has high power and large capacity.

However, various kinds of combustible materials are contained in thelithium secondary battery. As a result, the lithium secondary batterymay be heated or explode due to overcharge of the lithium secondarybattery, overcurrent in the lithium secondary battery, or other externalphysical impact applied to the lithium secondary battery. That is, thesafety of the lithium secondary battery is very low. Consequently,safety elements, such as a positive temperature coefficient (PTC)element and a protection circuit module (PCM), to effectively control anabnormal state of the lithium secondary battery, such as overcharge ofthe lithium secondary battery or overcurrent in the lithium secondarybattery, are loaded on a battery cell in a state in which the safetyelements are connected to the battery cell.

Generally, the PCM is electrically connected to the battery cell viaconductive nickel plates by welding or soldering. That is, nickel platesare connected to electrode tabs of the PCB by welding or soldering, andthe nickel plates are connected to electrode terminals of the batterycell by welding or soldering. In this way, the PCM is connected to thebattery cell to manufacture a battery pack.

It is required for the safety elements, including the PCM, to bemaintained in electrical connection with the electrode terminals of thebattery cell and, at the same time, to be electrically isolated fromother parts of the battery cell. To this end, a plurality of parts isnecessary, which complicates an assembly process of the battery pack. Inaddition, a space necessary to receive the battery cell is reduced.

Furthermore, a battery case to receive the parts is made of conductivemetal exhibiting high electric conductivity, such as metal plated withaluminum, an aluminum alloy, or nickel. As a result, a short circuit maybe caused in the battery cell when the battery case contact other partsof the battery cell.

Consequently, there is a high necessity for a battery cell that iscapable of securing a receiving space and insulativity of the batterycell and, at the same time, preventing the outer surface of a batterycase from being corroded or worn while using a conventional battery celland a conventional assembly method.

DISCLOSURE Technical Problem

Therefore, the present invention has been made to solve the aboveproblems and other technical problems that have yet to be resolved.

As a result of a variety of extensive and intensive studies andexperiments to solve the problems as described above, the inventors ofthe present application have developed a battery cell wherein a batterycase is anodized to improve insulativity and capacity of the batterycell and completed the present invention.

Therefore, it is an object of the present invention to provide a batterycell wherein the outer surface of an aluminum battery case is anodizedto improve corrosion resistance, wear resistance, and insulativity ofthe battery case.

Technical Solution

In accordance with one aspect of the present invention, the above andother objects can be accomplished by the provision of a battery cellincluding an electrode assembly of a cathode/separator/anode structure,the electrode assembly being impregnated with an electrolyte, theelectrode assembly being chargeable and dischargeable, a battery case inwhich the electrode assembly is mounted, the battery case being made ofaluminum or an aluminum alloy, and an alumina coating layer applied toat least a portion of an outer surface of the battery case by anodizing.

In the battery cell according to the present invention, therefore,durability and corrosion resistance of the battery case are improvedthrough anodizing of the battery case. Also, dyeing of the battery caseis possible due to small porosity and fiber property thereof, therebyimproving wear resistance and utility of the battery case.

The battery case may have various forms. For example, the battery casemay be a prismatic metal container; however, the battery case is notlimited thereto.

In a preferred example, the alumina coating layer may be applied to theouter surface of the battery case in a state in which an uncoated marginsection having a predetermined length is provided downward from an outercircumference of an upper end of the battery case. The uncoated marginsection provides easily weldability, for example, when laser welding iscarried out after a cap plate is mounted to an open upper end of thebattery case.

More preferably, the uncoated margin section extends downward from theouter circumference of the upper end of the battery case by a length of0.5 to 5 mm. If the length of the uncoated margin section is too long,it may be difficult to achieve desired durability of the battery casebased on surface treatment, which is not preferable. On the other hand,if the length of the uncoated margin section is too short, it may not bepossible to easily carry out laser welding, which is not preferable.

The method of forming the uncoated margin section is not particularlyrestricted. For example, the uncoated margin section may he formed byanodizing the battery case in a state in which an insulation material isapplied to the battery case or an insulator or an insulation tape ismounted or attached to the battery case and removing the insulationmaterial, the insulator, or the insulation tape.

In a preferred example, the alumina coating layer may have a thicknessof 0.01 to 0.05 mm.

The battery cell is activated during manufacturing of the battery cell.A battery cell activation process is a process of initially charging anddischarging the battery cell in a state in which the electrode assemblyis impregnated with an electrolyte to forming a protective film on ananode surface. Two battery cell activation processes may be performeddepending upon charge pin connection methods. Correspondingly, theconstruction of the battery cell according to the present invention maybe modified.

The first battery cell activation process may be performed in a state inwhich a cathode charge pin and an anode charge pin are connected to anupper end of the battery cell, and the alumina coating layer may beapplied throughout a bottom of the battery case.

The second battery cell activation process may be performed in a statein which an anode (or cat)ode) charge pin is connected to an upper endof the battery cell and a cathode (or anode) charge pin is connected toa lower end of the battery cell, and the alumina coating layer may beapplied to a bottom of the battery case excluding a connection openingsection, to which the cathode (or anode) charge pin is connected.

The shape of the connection opening section is not particularlyrestricted so long as the connection opening section corresponds to thecharge pins. For example, the connection opening section may be formedin a circular, oval, or polygonal shape in plan.

The connection opening section may be formed by anodizing the batterycase in a state in which an insulation material is applied to a portionof the bottom of the battery case or an insulator or an insulation tapeis mounted or attached to a portion of the bottom of the battery caseand removing the insulation material, the insulator, or the insulationtape.

In another preferred example, the battery case may be a cylindricalbattery case.

The alumina coating layer may applied throughout a side of thecylindrical battery case.

A battery cell activation process, which is carried out duringmanufacturing of the battery cell, may be performed in a state in whicha cathode (or anode) charge pin is connected to an upper end of thebattery cell and an anode (or cathode) charge pin is connected to alower end of the battery cell, and the alumina coating layer may beapplied to a bottom of the battery case excluding a connection openingsection, to which the anode (or cathode) charge pin is connected.

Specifically, the connection opening section may be farmed by anodizingthe battery case in a state in which an insulation material is appliedto a portion of the bottom of the battery case or an insulator or aninsulation tape is mounted or attached to a portion of the bottom of thebattery case and removing the insulation material, the insulator, or theinsulation tape.

In the above-mentioned examples, the connection opening section may besealed using an insulation member after the battery cell activationprocess.

The material for the insulation member is not particularly restricted solong as the insulation member protects the connection opening sectionfrom the outside and maintains electrical insulation of the connectionopening section.

The kind of the battery cell is not particularly restricted. Forexample, the battery cell may be a lithium secondary battery. Thesecondary battery may be a single battery including one battery cell oran assembled battery including two or more battery cells. Therefore, thesecondary battery is not denoted by a specific title.

The composition, structure, and manufacturing method of the secondarybattery. including the lithium secondary battery, is obvious to a personhaving an ordinary skill in the part to which the present inventionpertains, and therefore, a detailed description thereof will be omitted.

In accordance with another aspect of the present invention, there isprovided a secondary battery pack including the battery cell with theabove-stated construction mounted in a pack case. The secondary batterypack may be an embedded pack.

In accordance with a further aspect of the present invention, there isprovided a mobile device including the secondary battery pack with theabove-stated construction embedded therein as a power source.Specifically, the mobile device may be a thin laptop computer, a tabletPC, or a smart pad; however, the mobile device is not limited thereto.

Also, the secondary battery pack may be used as a power source for anelectric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybridelectric vehicle (PHEV), or a power storage device.

The above device or apparatuses are well known in the part to which thepresent invention pertains, and therefore, a detailed descriptionthereof will be omitted.

EFFECTS OF THE INVENTION

As is apparent from the above description, the entire surface of thebattery case is anodized in a state in which the connection openingsection is provided at the bottom of the battery case, thereby improvingcorrosion resistance, wear resistance, and insulativity of the batterycase.

Also, an additional process of attaching a label to the outer surface ofthe battery case is not necessary, thereby easily manufacturing thebattery cell and providing capacity greater than that of other batterycells having the same standard.

DESCRIPTION OF DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an exploded perspective view showing a battery pack accordingto an embodiment of the present invention;

FIG. 2 is a partial perspective view showing the upper end of a batterycell according to an embodiment of the present invention;

FIG. 3 is a partial side view of FIG. 2;

FIG. 4 is a front view showing the battery cell to which connectionpins, which are used during a charging process to activate the batterycell, are coupled;

FIG. 5 is an exploded perspective view showing the battery cell, ananodized part, and an insulation tape;

FIG. 6 is a partial perspective view showing the lower end of thebattery cell;

FIG. 7 is an exploded perspective view showing a cylindrical batterycell according to another embodiment of the present invention and ananodized part; and

FIG. 8 is a bottom view showing the bottom of the cylindrical batterycell according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Now, preferred embodiments the present invention will be described indetail with reference to the accompanying drawings. It should be noted,however, that the scope of the present invention is not limited by theillustrated embodiments.

FIG. 1 is an exploded perspective view typically showing a secondarybattery pack according to an embodiment of the present invention.

Referring to FIG. 1, a secondary battery pack 100 according to thepresent invention includes a battery cell 110, an insulative mountingmember 220, a protection circuit board 230, a pair of connection members210 and 212, a top cap 240, and a battery ease 150 having an anodizedpart 155. The insulative mounting member 220, the connection members 210and 212, the protection circuit board 230, and the top cap 240 aresequentially mounted to the top of the battery cell 110.

The insulative mounting member 220 is provided with openings (notshown), through which electrode terminals 253 and 254 of the batterycell 110 are exposed. The insulative mounting member 220 is directlyloaded on the top of the battery cell 110. The insulative mountingmember 220 may be coupled to the top of the battery cell 110 using abonding agent.

The insulative top cap 240 is coupled to the upper end of the batterycell 110 while surrounding the insulative mounting member 220 in a statein which the connection members 210 and 212 and the protection circuitboard 230 are loaded on the insulative top cap 240. Also, the insulativetop cap 240 extends downward by a predetermined length to surround theouter circumference of the upper end of the battery cell 110.

FIG. 2 is a partial perspective view showing the upper end of a batterycell according to an embodiment of the present invention, FIG. 3 is apartially enlarged side view of FIG. 2, FIG. 4 is a front view showingthe battery cell to which connection pins, which are used during acharging process to activate the battery cell, are coupled, FIG. 5 is anexploded perspective view showing the battery cell, an anodized part,and an insulation tape, and FIG. 6 is a partial perspective view showingthe lower end of the battery cell. For the convenience of description,the anodized part is shown in a state in which the anodized part isseparated from the battery case in FIG. 5. whereas the anodized part isshown in a state in which the anodized part is not separated from thebattery case in FIG. 6.

Referring to these drawings, the entire surface of the battery case 150is anodized (155) in a state in which an uncoated margin section 151having a length h of about 3 mm is provided downward from the outercircumference of the upper end of the battery case 150. The uncoatedmargin section 151 is formed by anodizing the battery case 150 in astate in which an insulation material (not shown) is temporarily appliedto the battery ease 150 and removing the insulation material.

Also, the battery cell 110 having an electrode assembly of acathode/separator/anode structure disposed in the battery case 150 madeof aluminum together with an electrolyte in a sealed state ismanufactured as follows. First, the entire surface of the battery case150 is anodized (155) in a state in which a connection opening section162, to which charge pins 160 and 161 used to activate the battery cell110 are connected, is formed at the bottom 159 of the battery case 150.Subsequently, the electrode assembly is mounted in the battery case 150,laser welding is carried out at he open upper end of the battery case150 along the outer circumference of the battery cell 110 above a capplate 152 (see an arrow shown in FIG. 2), an electrolyte is injectedthrough an electrolyte injection port 153 of the cap plate 152, and thebattery cell is activated. Subsequently, the electrolyte is replenished,and then the electrolyte injection port 153 is sealed.

The connection opening section 162 is formed in a quadrangular shape inplan. Alternatively, the connection opening section 162 may be formed invarious shapes in plan.

Also, the connection opening section 162 is formed by anodizing (155)the battery case 150 in a state in which an insulation material (notshown) is applied to a portion of the bottom of the battery case 150 andremoving the insulation material.

Finally, the connection opening section 162 is sealed using aninsulation member 165, such as an insulation tape.

The battery cell activation process is performed in a state in which thefirst charge pin 160 is connected to an upper electrode terminal 131 ofthe cap plate 152 and the second charge pin 161 is connected to theconnection opening section 162 of the battery case 150.

Consequently, the connection of the second charge pin 161 is easilyachieved by the provision of the connection opening section 162.

FIG. 7 is an exploded perspective view showing a cylindrical batterycell according to another embodiment of the present invention and ananodized part, and FIG. 8 is a bottom view showing the bottom of thecylindrical battery cell according to the embodiment of the presentinvention. For the convenience of description, the anodized part isshown in a state in which the anodized part is separated from thebattery case in FIG. 7.

Referring to these drawings, a cylindrical battery cell 300 has anelectrode assembly disposed in a cylindrical battery ease 350 togetherwith an electrolyte in a sealed state. The entire surface of the batterycase 350 excluding a connection opening section 360, to which chargepins (not shown) used to activate the battery cell 300 are connected, isanodized (500).

A cathode terminal 320 is formed at the top 310 of the cylindricalbattery cell 300 such that the cathode terminal 320 protrudes upward ina state in which the cathode terminal 320 is isolated from the batterycase 350. An anode terminal 330 is formed at the bottom of the batterycell 300.

Anodizing (500) the entire surface of the battery case 350 excluding theconnection opening section 360 of the cylindrical battery cell 300 isidentical to what has been described above with reference to FIGS. 1 to6 except that the uncoated margin section 151 (see FIG. 3) is formed,and therefore, a description thereof will he omitted.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. A battery cell comprising: an electrode assembly of acathode/separator/anode structure, the electrode assembly beingimpregnated with an electrolyte, the electrode assembly being chargeableand dischargeable; a battery case in which the electrode assembly ismounted, the battery case being made of aluminum or an aluminum alloy;and an alumina coating layer applied to at least a portion of an outersurface of the battery case by anodizing.
 2. The battery cell accordingto claim 1, wherein the battery case is a prismatic battery case.
 3. Thebattery cell according to claim 2, wherein the alumina coating layer isapplied to the outer surface of the battery case in a state in which anuncoated margin section having a predetermined length is provideddownward from an outer circumference of an upper end of the batterycase.
 4. The battery cell according to claim 3, wherein the uncoatedmargin section extends downward from the outer circumference of theupper end of the battery case by a length of 0.5 to 5 mm.
 5. The batterycell according to claim 1, wherein the uncoated margin section is formedby anodizing the battery case in a state in which an insulation materialis applied to the battery case or an insulator or an insulation tape ismounted or attached to the battery case and removing the insulationmaterial, the insulator, or the insulation tape.
 6. The battery cellaccording to claim 1, wherein the alumina coating layer has a thicknessof 0.01 to 0.05 mm.
 7. The battery cell according to claim 2, wherein abattery cell activation process, which is carried out duringmanufacturing of the battery cell, is performed in a state in which acathode charge pin and an anode charge pin are connected to an upper endof the battery cell, and the alumina coating layer is applied throughouta bottom of the battery case.
 8. The battery cell according to claim 2,wherein a battery cell activation process, which is carried out duringmanufacturing of the battery cell, is performed in a state in which ananode (or cathode) charge pin is connected to an upper end of thebattery cell and a cathode (or anode) charge pin is connected to a lowerend of the battery cell, and the alumina coating layer is applied to abottom of the battery case excluding a connection opening section, towhich the cathode (or anode) charge pin is connected.
 9. The batterycell according to claim 8, wherein the connection opening section isformed by anodizing the battery case in a state in which an insulationmaterial is applied to a portion of the bottom of the battery case or aninsulator or an insulation tape is mounted or attached to a portion ofthe bottom of the battery case and removing the insulation material, theinsulator, or the insulation tape.
 10. The battery cell according toclaim 1, wherein the battery case is a cylindrical battery case.
 11. Thebattery cell according to claim 1, wherein the alumina coating layer isapplied throughout a side of the battery case.
 12. The battery cellaccording to claim 10, wherein a battery cell activation process, whichis carried out during manufacturing of the battery cell, is performed ina state in which a cathode (or anode) charge pin is connected to anupper end of the battery cell and an anode (or cathode) charge pin isconnected to a lower end of the battery cell, and the alumina coatinglayer is applied to a bottom of the battery case excluding a connectionopening section, to which the anode (or cathode) charge pin isconnected.
 13. The battery cell according to claim 8, wherein theconnection opening section is formed by anodizing the battery case in astate in which an insulation material is applied to a portion of thebottom of the battery case or an insulator or an insulation tape ismounted or attached to a portion of the bottom of the battery case andremoving the insulation material, the insulator, or the insulation tape.14. The battery cell according to claim 8, wherein the connectionopening section is sealed using an insulation member after the batterycell activation process.
 15. The battery cell according to claim 1,wherein the battery cell is a lithium secondary battery cell.
 16. Asecondary battery pack comprising a battery cell according to claim 1mounted in a pack case.
 17. The secondary battery pack according toclaim 16, wherein the secondary battery pack is an embedded pack.
 18. Amobile device comprising a secondary battery pack according to claim 16embedded therein as a power source.